from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session, sessionmaker, declarative_base

engine = create_engine("postgresql+psycopg2://postgres:postgres@localhost:5433/query_builder")
db_session = scoped_session(sessionmaker(autocommit=False,
                                         autoflush=False,
                                         bind=engine))
Base = declarative_base()
Base.query = db_session.query_property()


def init_db():
    # import all modules here that might define models so that
    # they will be registered properly on the metadata.  Otherwise
    # you will have to import them first before calling init_db()
    Base.metadata.create_all(bind=engine)


def shutdown_session(exception=None):
    db_session.remove()


def init_app(app):
    init_db()
    app.teardown_appcontext(shutdown_session)
